This application claims priority of Japanese Application No. 2000-209579 filed Jul. 11, 2000, the completed disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a fuel supply system of a diesel engine using a common rail for pressing and holding a fuel to be supplied to each injection nozzle of an engine.
2. Description of the Related Art
As shown in FIG. 16, in the case of the fuel supply system of this type, a single fuel injection pump 102 and a single common rail 103 is conventionally provided for the outside of an engine 101. The single common rail 103 is provided at the fuel injection pump 102 installed below an intake manifold 109 in parallel with a crankshaft. One end of each of a plurality of injection nozzles 106 is inserted into a cylinder head 104 every cylinder and the other ends of the injection nozzles are covered with a cylinder head cover 105. The common rail 103 is connected to the fuel injection pump 102 through a single first fuel pipe 107 and connected to the injection nozzles 106 through a plurality of second fuel pipes 108. The common rail 103 holds a pressurized fuel to be supplied to each injection nozzle 106. Reference numeral 115 in FIG. 16 denotes a pressure sensor for detecting a fuel pressure in the common rail 103.
However, in the case of the above conventional diesel-engine fuel supply system, it is necessary to lay out a plurality of second fuel pipes 108 at the outside of the engine 101 while avoiding interference objects as shown in FIG. 16. Therefore, these second fuel pipes 108 respectively become long and have a complex shape and thereby, there arise problems in that the weight of a fuel supply system increases and the manufacturing cost increases.
It is an object of the present invention to provide a diesel-engine fuel supply system decreased in weight and cost and improved in outside quality.
It is another object of the present invention to provide a diesel-engine fuel supply system allowing an inexpensive pressure sensor having a low oil resistance to be used as a pressure sensor for detecting a fuel pressure in a common rail by preventing oil in a cylinder head cover from being splashed on.
The first aspect of the present invention is improvement of an engine including a plurality of injection nozzles one ends of which are respectively inserted into a cylinder head every cylinder and other ends of which are covered with a cylinder head cover and a single common rail provided in parallel with a crankshaft, the common rail being connected to a fuel injection pump through a single first fuel pipe and being connected to a plurality of injection nozzles through a plurality of second fuel pipes.
The characteristic configuration lies in the fact that the common rail is housed in a cylinder head cover, the front end of a first short pipe protruded from the common rail faces a first insertion portion formed in the sidewall of the cylinder head, and the first fuel pipe is connected to the first short pipe through the first insertion portion.
According to the diesel-engine fuel supply system of the first aspect, it is possible to decrease the length of a second fuel pipe for connecting between each injection nozzle provided every cylinder and a common rail and it is only necessary to dispose not a plurality of second fuel pipes but the single first fuel pipe at the outside of a cylinder head cover.
The second aspect of the present invention further comprises a pressure sensor for detecting a fuel pressure in a common rail, wherein the front end of a second short pipe protruded from the common rail protrudes outward by passing through a second insertion portion formed in the sidewall of a cylinder head and the pressure sensor is installed at the front end of the second short pipe.
According to the diesel-engine fuel supply system of the second aspect, the pressure sensor is located at the outside of the cylinder head cover. Therefore, oil in the cylinder head cover is hardly splashed on the pressure sensor.